Piezoelectric photoacoustic spectra of CuInSe2 thin film grown by molecular beam epitaxy

A CuInSe2 (CIS) film with Cu/In ratio of gamma = 1.79 has been grown on (00 1) oriented GaAs substrate by molecular beam epitaxy (MBE) at substrate tem perature of T-S = 450 degrees C. Piezoelectric photoacoustic (PPA) spectra were measured at liquid nitrogen and room temperatures. Two signals due to the non-radiative carrier recombination that correspond to bandgap energies of CIS and GaAs substrate were obtained. After illuminating with secondary light (lambda = 1100 nm), two additional PPA peaks were observed for the C IS film at liquid nitrogen temperature. These signals are due to intrinsic defects in the Cu-rich CIS film. (C) 1999 Elsevier Science S.A. All rights reserved.